In filling apparatus of the type with which the present invention is primarily concerned, the containers which are to be filled with liquid product such as beer or carbonated soft drink, for example, are continuously maintained in a fixed horizontal plane in entering into, moving through and exiting from the filling machine and the individual filling valves are provided with vertically movable centering sleeves adapted to be lowered onto the containers after entry into the filler to provide both for the centering of the can relatively of the valves and the sealing of the can to the valves A filling valve of this general type is shown and described in detail in U.S. Pat. No. 3,807,463, dated Apr. 30, 1974, assigned to Holstein and Kappert.
As shown in the aforesaid patent, the centering sleeve is movable under the control of a shifter mechanism or other suitable means between an elevated position above the plane of the incoming containers whereby to allow the latter to enter freely into the filler and a lowered or operative position in which a resilient sealing ring or gasket carried in the lower end of the sleeve is in engaged, sealing relation with the rim or mouth of the container. The sleeve remains in engaged, sealing relationship with the can or other container as the latter is first counter-pressurized and then filled to a pre-determined level with liquid product. When filling is completed, the sleeve is caused to be raised from the can or other container by its associated shifter or other actuator mechanism to permit the filled can to move out of the filler mechanism. With this valve design, the can remains in a fixed, horizontal plane while moving into, through, and off the filler onto the seamer transfer, thus, insuring maximum can stability and minimum product agitation during the course of the filling operation. At the same time, by moving the sleeve vertically rather than the cans themselves as in conventional filler apparatus, there is no requirement for lift cylinders. This results in a filler of substantially overall simpler construction and one which is far easier to maintain.
The advantages of this general type of valve are well known in the industry but there remain a number of limitations or drawbacks preventing an even wider acceptance of such valves. For one thing, these valves are still somewhat complicated of construction and design, particularly as concerns the mechanism for controlling the vertical movement of the sleeve member. Because of this, the reliability and efficiency of this type of valve has been adversely affected. Additionally, the cost of manufacturing the valve has been relatively high, along with maintenance costs.
Then too in these valves wherein the sealing of the can to the valve is effected by the engagement of a resilient gasket carried in the lower end of the sleeve with the rim or mouth of the can, a sufficient pressure or force must be exerted on and between the can and sleeve to cause sealing compression of the gasket. This force may typically be derived from a suitable compression spring associated with the movable sleeve or through a toggle linkage of the over center acting type which when activated moves the sleeve into sealing engagement with the can and holds the same in place during the course of the filling cycle.
In either case, the forces against the can may become fairly appreciable and, in filling certain cans particularly those of deep drawn construction and formed of a lightweight readily deformable material such as aluminum, these pressures or forces can cause a crumpling or deformation of the can. Obviously, in any such eventuality, the can will not be properly filled and necesarily must be discarded or removed from the filling machine. With the increasing usage in industry of aluminum cans having wall thicknesses of ever decreasing gauge, there is a clear and present need for a valve which can sealingly engage the can with a minimum of force or pressure exerted against the sidewalls of the can.
A further concern in the use of these lightweight aluminum cans in present day canning lines of breweries and soft drink plants stems from the high susceptibility of these cans to denting or crumpling during handling in the filling line. The rims or upper ends of these cans are particularly susceptible of becoming out-of-round and/or sustaining dents or deformities in the course of being removed from storage and placed into the stream of cans in the filling lines.
Inasmuch as the mouth of the can is required to register with the gasket in the centering sleeve to form a seal with the valve, it becomes almost impossible or exceedingly difficult to properly seal the can to the filling valve if the mouth of the can is nicked or dented. Inevitably in these instances, the can cannot receive any liquid or receives less than the desired quantity of liquid, requiring the can and product to be discarded. Filling efficiencies are thereby adversely effected and overall costs of operation are increased as a consequence.